Thread-rolling machine



July 2, 1929. c. D. MCDONALD 1,719,230

THREAD RQLLING MACHINE Filed Jun 21, 1928 Y 4 Sheets-Sheet 1 67/266 Z/WZozzaZZ,

y 2, 1929- c. D. M DONALD .719.230

THREAD ROLLING MACHINE Filed June 21. 1928 4 Sheets-Sheet 2 Q *ZZarZwiJ/ZW ZZ July 2, 1929. D, McDONALD 1.719.230

THREAD ROLLING MACHINE Filed June 21, 1928 4 She ets-Sheet 4 Patented July 2, 19 I UNITED STATES PATENT OFFICE.

CHARLES D. MeDONALD. OFCHICAGO, ILLINOIS, ASSIGNOR T M noNALn MACHINE 00., or CHICAGO, ILLINOIS, A CORPORATION or ILLINOIS.

THREAD-ROLLING MACHINE.

Application filed June 21,

This invention relates to thread rolling machines, and one of its objects is to provide novel means for placing the work upon the thread rolling means, or other tool, and discharging ittherefrom. Another object is to provide means for automatically stopping the machine in case the work causes an obstruction to the work placing or replacing mechanism.

The invention has particular reference to thread rolling machines for rolling knurled portions or threads in covers for cans or jars. Occasionally a cover becomes misplaced in the .arrier, which conveys the cover to the knurliug and thread rolling tools, with the resultthat injury is likely to occur to some of the parts of the machine in the act of placing a cover on the thread rolling tool or discharg ing it therefrom. In accordance with the present invention, an automatically operating release device is provided, which is made effective to stop the machine whenever the mechanism which places the articles upon the thread rolling spindle, or removes it therefrom, meets with resistance suflicicnt to overcome certain members of the release mechanism. I

The invention consists, therefore, in a thread rolling machine having a lever for rcciprocating the mechanism which places the work upon the thread rolling spindle, or other tool. and removes it therefronn said lever havin an adjustable fulcrum whereby the length of its stroke may be varied to accommodate articles of various sizes. The invention further consists in automatic release mechanism interposed between said lever and the placing and replacing mechanism and operative con-- nections with the starting mechanism of the machine, whereby the machine is automati cally stopped whene er the release mechanisln is actuated as a resultof said placing and replacing mechanism meeting with an obstruction.

The invention further consists in the sevcral novel features of construction, arrangement and combination of parts hereinafter fully set forth and claimed.

The invention, is clearly illustrated in the drawings accompanying this specification in which- Figure 1 is a side elevation of a thread rolling machine embodying a simple form of the present invention; p 7

Fig. 2 is an end elevation thereof, partly 1928. Serial N0. 287,326.

broken away, looking in the direction of the arrow 2 in Fig. 1;

Fig. 3 is a fragniental' vertical section taken on the line 3-3 of Fig. 1;

Fig. 4 is a detail elevation, partly broken away, of the work placing and replacing mechanism A Fig. 5 is a detail end elevation of the lever seen in Fig. l, andcertain associated parts, looking in the direction of the arrow 5 in F s Fig. 6 is a detail end elevation of certain members of the lever release mechanism looking in the direction of the arrow 5 in Fig. 4;

Fig. 7 is a view, part1 in plan and partly in horizontal section, 0 the cam block and lever, the line of section being indicated at 7-7 in Figs. 2 and 4:;

Fig. 8 is a detail View, partly in end elevation and partly in vertical crosssection, taken on the line 8-8 of Fig. 4;

Fig. 9 is a detail vertical longitudinal section taken on the line 9-9 of Fig. 8;

Fig. 10 is a viewsimilar to Fig. 9, but showing the parts in a different position;

Fig. 11 is a detail vertical cross-section illustrating certain of the transmission gears for the shafts of the machine;

Fig. 12 is a detail cross-section of the delivery chute taken on the line 12-12 of Fig. 3.

Fig. 13 is a detail view, partly in side ele vation and partly in vertical longitudinal section, showingthe connection between the turret wheel and its shaft; and

Fig. 14.- is a vertical cross-section taken on the line 14-14 of Fig. 13.

Referring to said drawings, which illustrate a simple embodiment of the present invention, the reference character 13 designates the main frame of the machine upon which the several operating mechanisms are mounted. A turret wheel 14;, having equidistant notches in its periphery for the reception of the work, is provided, and, as shown, said turret wheel is mounted upon a shaft 1.5 journaled in suitable bearings carried by the frame of the machine and driven in an intermittent or step by step movement, preferably by the usual Geneva movement mechanism comprising the disk 16, and a roller 17, the latter being carried by a. gear wheel 18 whiehmeshes with a pinion 19 loosely mounted on a continuously driven shaft Q0 of the machine.

' ing lever, the spring 27 instant Rigidly mounted on the shaft is a continuously rota-ting gear wheel 21 which is driven from some suitable source of power. Clutch mechanismis provided between the shaft 20 and pinion. 19, which clutch mechanism comprises a clutch collar 22 fast on the shaft 20 and having jaws engaging with 00- acting jaws on the pinion 19. e

A clutch actuating arm 23 engages with the clutch collar 22and is ar 'anged to clutch and uriclutch the pinion 19 from the shaft 20, whereby the operating mechanism of the machine is started and stopped. The clutch arm 23 is mountedupon a rock shaft 24:, which is rotatably mounted in the frame of the machine and protrudes from one side thereof, as seen in Fig. 1, and upon said rock shaft24'is rigidly mounted the starting and stopping hand lever'25 of the machine. By moving the lever 25 in the proper direction, the pinion I9 is thereby connected to the continuoiisly moving shaft 20 and the machine is set into operation, and by moving the lever in the opposite direction, the pinion 19 is unclutched and the mechanism of the machine is stopped.

One arm 26 Ofthestarting lever 25 is connected to a tension spring 27, the other end of which is connected to the press frame, and

thetension of said spring is exerted to move the-starting lever-into its stopping position. A detentbr other latch device 28 is mounted upon the frameof the machine and engages witha lug orother shoulder 29 on the arm 26 ofthe: starting lever 25 under normal working conditions of the machine, but is'arranged to be disengaged from'said lug whenever an abnormal condition arises in the work placing and replacing mechanism. The spring 27'holds the starting lever 25 in engagement ,with the detent 28, and when- .ever said detentis released from the start- I I ly moves the starting lever 'into' its stopping position, thereby unclutchingthe pinion 19 from the shaft 20. I I I I The machine is provided with a forming tool such as a knurling or thread rolling spindle 3O journaled in the frame of the machine and'driven from the pinion 19 by suitable driving connections (not shown). (Io-operating with said spindle 30 is a companion knurling or thread rolling spindle 31 which is mounted ina swinging frame 32 carried by the main frame of the machine. The spindle 31 is also provided with drivconnections (not shown) operated from the pinion 19, and means are provided for swinging the swinging frame 32 and thereby moving-the spindle 31 into close proximity to the spindle 30, whereby the work is acted upon by the two spindles. Inasmuch as the thread rolling mechanism forms no part of the present invention, the. construction and means for operating the same have not been shown or described in detail.

In the present instance, the invention has been illustrated in connection with a thread rolling machine for rolling a thread upon covers of cans or jars, such a cover being shown at 33 in Fig. 10, and the blank from which the threaded cover is made, being shown at 33 in Fig. 9. The blanks are led to the turret wheel 141; through an inclined delivery chute 34; and enter the notches in the turret wheel andv are carried by it to and pastthe thread rolling spindle.

In the form of the invention illustrated, the turret wheel lel stands in a vcrl ical plane and the blanks 33 roll down the inclined chute with their hollow sides facing the end of the thread rolling spindle 30. The spindles extend at right angles to the turret wheel, and in the operation of the machine, the turret wheel is intermittently rotated so as to bring its notches one at a time into co-axial alignment with the thread rolling spindle 351), where it remains stationary for a brief interval of time, at which time a. blank is moved from the notch (which is in alignment with the spindle) and placed upon the spindle, after which the companion thread rolling spindle ismoved into effective engagement with the rim or flange of the blank and the thread or other impression is rolled out by the two spindles.

Thereafter, the swinging thread rolling spindle 31 is retracted and the finished article is stripped from the thread rolling spindle 30 and moved back into the notch in the turret wheel formerly occupied by it. The turret wheel is then moved forward one step and another blank moved into co-axial alignment with the spindle 30 and the same opera.- tion perforn'ied as before. A discharge chute 35 isprovided below and at the side of the turret wheel into which the finished articles fall when they reach a position on the pcriphery of the turret wheel where they escape by gravity from the notches.

Supported at one side of the turret wheel in co-axial alignment with the thread rolling spindle 30 is a work placing linger 30. which is arranged to push the blanks out of the notches of the turret wheel and place them upon the spindle in position to be openated upon by the two thread rolling spindles. On the other side of the turret wheel a work replacing plate 37 also arranged in coaxial alignment with the spindle 30, which plate is arranged to move in spaced relation to the work placing finger 36, so that as the finger moves the work upon the spindle, the plate recedes but remains in position to strip the finished work from the spindle and replace it in the notch in the turret wheel when the thread rolling operation has been performed.

The finger 36 is secured to an arm 38 (see till llll

Iii

Figs. 4 and 8) which is carried by a sleeve 39 clamped or otherwise secured to the arm 38 and slidably mounted upon a guide rod i0 fixedly secured in the frame of the machine. The rod 10 is parallel with the axes of the spindles 3'0 and 31 and furnishes a support for the sleeve 39 and parts carried thereby. The work replacing plate 37 is carried by an arm 11 also secured to the sleeve 39. The lower end of the arm 38 is grooved and rides upon a guide bar 1-2 secured to a bracket 43 mounted on the main frame of the machine. With certain kinds of work, it is necessary for several spindles or tools to operate on the work at ditlt'erent stations along the periphery of the turret wheel, and, for this reason, the arm 38 is arranged to support two or more work placing fingers and work replacing plates. The work replacing plate 37 is formed with a central opening arranged in co-axial alignment with the spindle 30, whereby the plate may move along said spindle, and it is also formed with a notch through which the movable thread rolling spindle may move laterally in engaging the work.

Mechanism is provided for reciprocating the placing and replacing members in timed relation to the intermittent movement of the turret wheel, and, as shown, said means comprises, among other mechanisms, a cam block 4 1 mounted upon a shaft 45 journaled in the bearings contained in theframe of the machine, and having a pinion 16 (see Fig. 11) on one end driven from the pinion 19 through intermediate gears. Associated with the cam block is a lever 17 which is mounted upon a bracket 48 and-has aroller 49 on one end,which stands in the cam. groove ot the cam block 44. The other arm of the lever 47 is connected to the sleeve 39 of the work placing and replacing 1necha- 'nisln by a link 50, pivotally connected to one end of the sleeve 39, and having a releasable connection with the lever 4:7, whereby in case either one ot the work placing or replacing members meets with an obstruction, the lever 17 will be .instantlyzreleased from its effective connection with the link 50.

As shown, the link 50 provided with a pair of spring-pressed. or clamp mem here 51 and 52having opposing grooves 53 on their inner edges, in which grooves is held a pin or roller 54: mounted on the upper arm of the lever 1-7. The jaw or clamp member 51 is rigidly secured to the link 50 and the lower jaw 52 is pivotally connected to the aw 51, whereby the two jaws may separate under excessive strain thereon.

A red 55 secured to the aw 52 and extending through the jaw 51, together with a spring 56 interposed between the jaw 51 and a nut upon the end of the rod 55, provides means for clamping the jaws 51 and. 52 upon the pin or roller 54. The arrangementot' theseparts ]S such. that in case e1ther of the work placing the throw of the lever.

or replacing members meets with an obstruction, thereby arresting movement of the sleeve 39, link 50, and the jaws 51 and 52, the lever, during the remainder of its stroke, moves the pin or roller 54 out of the notches 55, thereby spreading the jaws 51 and 52 apart, and as a result of such lateral movement oi the jaw 51, the starting lever 25 is actuated and the machine stopped instantly before any damage can be done to any of the working parts 01 the thread rolling mechai'iisui or work placing and replacing mechanism.

To one end of the jaw 51 is attached one end of a link or connecting rod 57, the other end of which is attached to one arm of a bellcrank lever 58 which is iulcrun'ied upon the bracket 18. To the otherarin of the bellcrank lever 58 connected one end ot a link or connecting rod 59, the other end of which is connected to one arm of a bell-crank lever 60 fulcrumed upon a bracket 61 secured to the frame of the machine. To the other end of the bell-crank lever 60 is connected one end oil? a link or connecting rod 62, the other en d. of which=is coni'iected to the detent or latch 28. its a preference, the jaw 51 is formed with a notch in its upper edge in which rests a pin 63 carried by the connecting rod 57. This arrangement permits the movement of the jaws 51 and 52 along an arc of a circle without disturbing the connection between the detent 28 and starting lever 25.

The bracket i8 is formed with a vertically slotted bracket arm 1:8 in which is adjustably mounted a bearing block 6 1 which is provided with a stud shaitt or spindle (35 that forms the fulcrum for the lever 47. The block ti-l-hasa threaded stem (36 which projects through the slot in the bracket arm 4-8 and is provided with a nut 67 upon itsouter end, whereby the blocklH- may be secured in any position of adjustment on the bracket arm 48. i i

A companion bearing block 68 is provided for the lever 47, which block is formed with a hollow boss 69 rotatz-ibly mounted on the stud shaft or spindle and is provided with a nut 70 threaded upon the boss (39 and adapted to clamn the lever 17 in any position of adjustment upon the bearing block 68. A collar 71 secured upon the stud shaft or spindle 65 holds the bearing block 68 and parts carried thereby upon the stud shaft (55. This arrangement provides nieans for varying the fulcrum ot the lever 47 to thereby vary By loosening the nuts 67 and 70, the bearing blocks (5 1 and (58 may be raised or lowered to change the tulcrum of the lever after which the nuts are screwed up to secure the parts in adjusted position.

Occasionally a blank or the finished article iecomes janinied between the turret wheel and some other part of the machine, for instance,

the thread rolling spindle, which is likely to cause serious injury to the machine unless the movement of the turret wheel is stopped instantly. It will be understood that there is considerable momentum in the rotating parts in themachine, and although the mechanism of the machine may have been disconnected from the source of power by the release mechanism, there may be, suliicient momentum left to carry the turret wheel on a short distance, thereby causing damage in case a blank or finished article is jammed in the turret wheel. g v

To avoid this contingency, the turret wheel 14 is connected to its shaft 15 by release mechanism which operates to couple the turret wheel to the shaft under ordinary working conditions of the machine, but allows the turret wheel to be dlsconnected from the shaft in case a am occurs which tends to arrestmovement of the turret wheel. As shown in Figs.

13 and 14, a sleeve 73 is keyed to the turret wheel shaft 15 and the turret wheel 14 has a hub portion 74 which is mounted upon the sleeve and connected thereto by a spring pressed finger 75, one end 76 of which is held in a notch 77 formed in the sleeve. The spring 78 is seated in a recess formed in the hub portion 74 and bears against the end 7 9 of the linger. The turret wheel 14 is held on the sleeve by a bolt secured in the shaft 15 and a washer 81, which is interposed between the head of the bolt 80 and the side of the turretwheel.

' The spring-pressed linger 75 operatively connects the turret wheel 14L with the shaft 15, whereby the turret wheel is positively rotated by the shaft. The end 76-of the ling er which engages in the notch 77 is beveled as seen in Fig. 14, whereby in case the turret wheel meets with an obstruction, as, for instance, 1f a blank or finished article becomes jammed between the turret wheel and some stationary part, the linger is forced out of the notch 77 against the action of the spring 78, thereby releasing the turret wheel 1& from the shaft 15, and permitting the shaft to rotate, but allowing the turret wheel to remain stationary and thereby to prevent injury to the machine. After the'jarnmed material has been removed, the turret wheel may be operatively connected with its shaft by turning it on the sleeve until the spring-pressed linger 75 engages in the notch 77.

In the operation of the machine, the turret wheel is rotated in an intermittent or step by step manner,-thereby bringing one 'of its notches into coaxial alignment with the thread rolling spindle or other tool 30. The blanks are received in the notches of the turret wheel at the bottom of the chute 34 and conveyed to the tool;

lVhen a blank has been brought into position in co-aXia-l alignment with the tool, the care. blocker swings the lever 43? in the direetioncf the arrew'thereen (see r),

thereby moving the placing and replacing members 36 and 37 toward the right, as viewed in Fig. 4, and, as a consequence, the work placing linger 36 engages the end walls of the blan r and moves it out of the notch in the turret wheel and places it upon the tool. Simultaneously therewith the work replacing member 37 recedes and remains in position around the tool and behind the blank. The companion tool is then brought down upon the blank and the knurled edge and thrca d is rolled upon the blank.

\Vhen the tools have finished their work, the cam of the cam block ll is in position to swingthe lever 17 back and the lever is then swung back and the work placing and replacing members returned to their former positions, the work replacing member 37 engaging with the edge of the finished article, stripping it from the tool and replacing it in the notch of the turret wheel. Simultaneously the work placing linger 36 recedes from the article and the turret whccl thereafter is advanced one step, thereby bringing another blank into co-axial alignment with the tool.

In case a blank is misaligned with respect to the tool, or is misplaced in the notch of the turret wheel, or in case any condition arises in which a malformation of the blank takes place, and either the work placing linger 36 or work replacing plate 337 meets with sntlicient resistance to'overcome the force of the spring 56, the continued movement of the lever 47 forces the pin or roller 54 out of the notches 53 of the jaws 51 and 52 and, as a consequence, spreads said jaws apart, thereby raising the upper jaw, which upward movement of the jaw lifts the link or connecting rod 57 and swings the bell-crank lever 58 as its fulcrum, and the latter swings the bell-crank lever 60 on its fulcrum,

through the inslrumentality of the link or connecting rod 59, and the bell-crank lever GO'draws the link or connecting rod (32 (see Fig. 1) toward the left as viewed in Fig. l, thereby swinging the detent 28 upon its l'ulcrum and releasing it from the starting lcvcr 25, whereupon the spring 27 swings the starting lever into stopping position, thereby unclutching the pinion 19 from the continuously driven shaft. 20 and stopping the. movement of the working parts of the machine, From the above it will be seen that in case of a malpositioning of the blank in the turret wheel, or in case either the work placing member or the work replacing member meets with abnormal condition of the work, that the operating parts of the machine are instantly stopped, thereby preventing inury to any of its parts.

lVhile the invention has been shown in connection with thread rolling tools, it is to he understood that any suitable tool or tools may be employed for performing rr'orlii upon the blank. It is also to be understood that more than one set of tools may be employed in the machine and that the work placing and replacing members may be duplicated for each station at which the tools perform their work.

. By the termwork placing Inen1be1",wherever it occurs in the specification and claims, is meant a device adapted the blank and force it from the notch of the turret wheel and place it on the tool, and that by the term work replacing member is meant a device for engaging with the a1.'ticle, stripping it or removing it from the tool and replacing it in the notch of the turret wheel. y i i More or less variation of the exact details of construction is possible Without departing from the spirit of this invention. I desire, therefore, not exact form of the construction shownand described, but intend in the following claims to point. out all of the invention disclosed herein. I

I claim: y y i 1. In a machine of the character described, the combination with a tool, a turret wheel,

a turret wheel shaft, and a releasable connection between the turret wheel and turret wheel shaft, of work placing and replacing mei'nbers, a power shaft, power driven mechanism for driving said turret .wheel shaft and operating said Work placing and replacing members, a releasable connection for said work placing and replacing members, and

means operated by said releasable connection for disconnecting the driven mechanism from the power shaft.

2. I11 a machine of the character described, the combmatlon with a tool, a turret wheel,

a shaft for said turret wheel, and a releasable connection between said turret wheel and shaft, of work placing and replacing members, operating mechanism therefor, power driven mechanism fol-said shaft, areleasable connection between said work placing and re-.

placing'members and the operating mechanism therefor, and mechanism operated by a member of said. releasable connection for stopping the operating mechanism of the.

machine.

i 3. In a machine of the character described, the combination with a tool, a turret wheel, a shaft for said turret wheel, and a releasable connection between said turret wheel and shaft, of reclprocatory work placing and replacing mechanism having spaced work place ing and replacing members, operating mecha: nism for reciprocating said work placing and replacing mechanism, power driven operating mechanism for said turret wheel shaft, a releasable connection between said placing and replacing mechanism and the operating mechanism therefor, and mechanism operated by a member of said releasable connection for to engage with to limit myself to the stopping the operating mechanism of the machine. i

41. In a machine of the character described, the combination with a tool and a turret wheel for conveying work to a position in co-axial alignment with the tool, of work placing and replacingmembers, reciprocatory supporting meansfor said work placing and replacing members, an oscillatory lever, a link releasably connecting said lever with said supporting means, and a lever oscillating cam cooperating with said lever to reciproc ate said work placing and replacing members.

5. I11 a machine of the character described, the combination with. a tool and aturret wheel for conveying work to a position in co-axial alignment with the tool, ofwork placing and replacing members, reciprocatory supporting means for said work placing and-replacing members, operating mechanism for reciprocating said work placing and replacing members, power driven operating meclmuism for the machine, and a releasable connection in said operating mechanism for the work placing and replacing members.

6. In a machine of the character described,

. the combination with a tool and a turret wheel for conveying work to the tool, of work placing .and replacing mechanism arranged in co-axial alignment with the tool, an osc1lla tory operating lever for actuating the work Dinnin and re alacin mechanism and releasably connected therewith, and means for os cillating said lever.

7. Ina machine of the character described, the combination with a tool, and a turret wheel i for conveying work to the tool, of work placing and replacing mechanism having two work engagingmembers, one at each side of the work and arrangedin co-axial alignment with the tool, an oscillatory operating lever for actuating said work placing and replacing mechanism, a link releasably connecting said work placing and replacing mechanism and lever, and means for oscillating said lever.

ing mechanism therefor, and mechanism operated by a memberof said releasable connection for stopping theoperating mechanism of the machine.

9. In amachine of the character described, the combination with a tool and a turret wheel forconveying work to a position in coaxial alignment with the tool, of work placing and replacing mechanism for shifting the work from the turret wheel to the tool and replacing the work on the turret wheel,

a drive shaft, driving mechanism for the machine driven thereby and including opermechanism and the work placing and replacing mechanism operating under the influence of abnormalyresistance to" the work placing and replacing mechanism to release the con- :nection between the work placing and replacing mechanism and the operating mechanism therefor.

' 10.111 a machine of'the character described,

the-combination with a tool and a turret wheelifor conveying Work to a position in eo-axialalignment with the tool, of work placing and replacing mechanism for shifting the work from the turret wheel to the tool and replacing the work on the turret fwhe'el, a drive shaft, driving mechanism for the machine driven thereby and including operating mechanism for the work placing and replacing mechanism, a releasable connecting member between said operating mechanism and the work placing and replacing'mechanism operating under the influence of abnormal resistance to the work placing and replacing mechanism to release the connection between the work placing and replacing mechanism and the operating mech anism therefor, and mechanism for disconnecting said driving mechanism from saiddriveshaft, operatively connected with the releasable connecting member.

-11QIn a machine of the character described, the combination with a tool and a turret wheel for conveying work to a position in martial alignment with the tool, of work placing and replacing mechanism for shifting the work from the turret wheel to the tool and replacing the work on the turret wheel, a drive shaft, driving mechanism for the machine driven thereby and including operating mechanism for the work placing and replacing mechanism, a releasable connecting member between said operating -mechanismand thework placing and replacing mechanism operating under the influence "of abnormal resistance to the work placing and replacing mechanism to release the connection between the work placing and replacing mechanism and the operating mechanism therefor, manually actuated mechanism for disconnecting the drive mechanism of the machine from said drive shaft, and operative connections between said manually actuated mechanism and said releasable connecting v member. a

V 12. In a machine ofthe character described, the combination with a tool and a turret wheel for conveying work to a position in co-axial alignment with the tool, of work placing and replacing mechanism for shifting the work from the turret wheel to the tool and replacing the work on the turret wheel, a drive sh a'l't, driving mechanism for the machine driven thereby and including operating mechanism for the work placing and replacing mechanism, a releasable connecting member between said operating mechanism and the work placing and replacing mechanism operating under the influence of abnormal resistance to the work placing and replacing mechanism to release the connection between the work placing and replacing mechanism and the operating mechanism therefor, clutch mechanism between said drive shaft and the driving mechanism for the machine, a manually actuated clutch lever, and operative connections between said clutch lever and said releasable connecting member for disengaging said clutch.

13. In a machine of the character described, the combination with a tool and a turret wheel for conveying work to a position in co-axial alignment with the tool, of work placing and replacing mechanism for shifting the work from the turret wheel to the tool and replacing the work on the turret wheel, a drive shaft, driving mechanism for the machine driven thereby and including operating meehanism for the work placing and replacing mechanism, spring-pressed separable jaws connected to said work placing and replacing mechanism, a cam operated lever having a member releasably connected to said jaws and arranged to spread them apart under an abnormal strain thereupon, a starting and stopping lever for the driving mechanism of the machine, and link connections between said starting and stopping lever and one of said jaws.

14. In a machine of the character described, the combination with a thread rolling tool and a turret wheel for (JOIIVONlHg work to said tool, of a work placing l'inge and a work replacing plate, co-operating to place the work on the tool and replace it on the turret wheel, a reciprocatory supporting member carrying said finger and plate, separable clamping jaws connected to said supporting member, and. a cam operated lever having a member held in releasable clamping engagement with said jaws and arranged to be released from its effective connection with said jaws when. the latter are subjected to an abnormal strain.

15. In a machine of the character described, the combination with a thread rolling tool and a turret wheel for conveying work to said tool, of a work placing finger and a work replacing plate (to-operating to place the work on the tool and replace it on the turret wheel, a reciproeatory supporting member carrying said finger and plate, separable clamping jaws connected to said supporting member, a cam operated lever having a member held in releasable clamping engagement with said jaws and arranged to be and driving mechanism, and a clutch throwing mechanism operatively connected with one of said clamping j aws and arrai'iged to be actuated thereby when the cam operated lever is released from its elieetive connection with the jaws.

CHARLES D. MCDONALD. 

